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Wang H. Synthesis, structure and reactivity of iminoborane radicals. Chem Commun (Camb) 2024; 60:3806-3809. [PMID: 38487988 DOI: 10.1039/d4cc00720d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
The synthesis, characterization and reactivities of iminoborane radicals were reported. Both X-ray analysis and density functional theory calculations revealed that the unpaired electron delocalizes over the N(1)-C(1)-B(1)-N(2) moiety. Radical trap reactions showed that this radical species acts as a boron radical. These reactions also serve as methods for the synthesis of Lewis base-stabilized oxyl-terminated iminoboranes.
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Affiliation(s)
- Hanqiang Wang
- Department of Chemistry and Dongguan Key Laboratory for Data Science and Intelligent Medicine, Great Bay University, Dongguan 523000, China.
- Department of Materials Science and Engineering, Southern University of Science and Technology (SUSTech), Shenzhen, Guangdong 518055, China
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2
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Gupta D, Einholz R, Bettinger HF. Strain induced reactivity of cyclic iminoboranes: the (2 + 2) cycloaddition of a 1 H-1,3,2-diazaborepine with ethene. Chem Sci 2024; 15:666-674. [PMID: 38179531 PMCID: PMC10763563 DOI: 10.1039/d3sc04901a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2023] [Accepted: 11/19/2023] [Indexed: 01/06/2024] Open
Abstract
Iminoboranes have gathered immense attention due to their reactivity and potential applications as isoelectronic and isosteric alkynes. While cyclic alkynes are well investigated and useful reagents, cyclic iminoboranes are underexplored and their existence was inferred only via trapping experiments. We report the first direct spectroscopic evidence of a cyclic seven-membered iminoborane, 1-(tert-butyldimethylsilyl)-1H-1,3,2-diazaborepine 2, under cryogenic matrix isolation conditions. The amino-iminoborane 2 was photochemically generated in solid argon at 4 K from 2-azido-1-(tert-butyldimethylsilyl)-1,2-dihydro-1,2-azaborinine (3) and was characterized using FT-IR, UV-vis spectroscopy, and computational chemistry. The characteristic BN stretching vibration (1751 cm-1) is shifted by about 240 cm-1 compared to linear amino-iminoboranes indicating a significant weakening of the bond. The Lewis acidity value determined computationally (LAB = 9.1 ± 2.6) is similar to that of boron trichloride, and twelve orders of magnitude lower than that of 1,2-azaborinine (BN-aryne, LAB = 21.5 ± 2.6), a six-membered cyclic iminoborane. In contrast to the latter, the reduced ring strain of 2 precludes nitrogen fixation, but it unexpectedly allows facile (2 + 2) cycloaddition reaction with C2H4 under matrix isolation conditions at 30 K.
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Affiliation(s)
- Divanshu Gupta
- Institut für Organische Chemie, Universität Tübingen Auf der Morgenstelle 18 72076 Tübingen Germany
| | - Ralf Einholz
- Institut für Organische Chemie, Universität Tübingen Auf der Morgenstelle 18 72076 Tübingen Germany
| | - Holger F Bettinger
- Institut für Organische Chemie, Universität Tübingen Auf der Morgenstelle 18 72076 Tübingen Germany
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3
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Dolati H, Denker L, Martínez JP, Trzaskowski B, Frank R. Iminoboranes With Parent B=NH Entity: Imino Group Metathesis, Nucleophilic Reactivity and N-N Coupling. Chemistry 2023; 29:e202302494. [PMID: 37584302 DOI: 10.1002/chem.202302494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 08/11/2023] [Accepted: 08/11/2023] [Indexed: 08/17/2023]
Abstract
While R2 C=N-R double bonds in organic imines are well established, the related iminoboranes R-B=N-R are either prone to oligomerization or can only be stabilized at sufficient steric congestion. In particular, the examples of unsubstituted parent B=N-H entity are rare. We demonstrate that the amino imidazoline-2-imine ligand system (HAmIm) not only gives rise to the isolation of a parent (AmIm)B=N-H iminoborane, but also to species of type (AmIm)B=N-SiMe3 with concomitant stabilization by lithium bromide. The double bond character in these systems is unambiguously corroborated by DFT calculations. The steric accessibility of the (AmIm)B=NH unit allows facile reactivity including metathesis reactions with C=O and C=S bonds, nucleophilic addition toward organic and organometallic carbonyl compounds, but also oxidative N-N coupling within a dimeric unit. Thus, the chemical behavior of the (AmIm)B=N-H and (AmIm)B=N-SiMe3 is distinctly different from that of organic imines.
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Affiliation(s)
- Hadi Dolati
- Institute of Inorganic and Analytical Chemistry, Technische Universität Braunschweig, Hagenring 30, 38106, Braunschweig, Germany
| | - Lars Denker
- Institute of Inorganic and Analytical Chemistry, Technische Universität Braunschweig, Hagenring 30, 38106, Braunschweig, Germany
| | - Juan Pablo Martínez
- Centre of New Technologies, University of Warsaw, Banacha 2 C, 02-097, Warszawa, Poland
| | - Bartosz Trzaskowski
- Centre of New Technologies, University of Warsaw, Banacha 2 C, 02-097, Warszawa, Poland
| | - René Frank
- Institute of Inorganic and Analytical Chemistry, Technische Universität Braunschweig, Hagenring 30, 38106, Braunschweig, Germany
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4
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Guo R, Hu C, Li Q, Liu LL, Tung CH, Kong L. BN Analogue of Butadiyne: A Platform for Dinitrogen Release and Reduction. J Am Chem Soc 2023; 145:18767-18772. [PMID: 37582249 DOI: 10.1021/jacs.3c07469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/17/2023]
Abstract
Exploration of the metallomimetic chemistry of main group elements is of the utmost importance from the perspective of both fundamental research and potential applications. Here, we report the synthesis, bonding analysis, and reactivities of an isolable diiminoborane, Mes*B≡N─N≡BMes* (Mes* = 2,4,6-tri-tert-butylphenyl) (1), a BN analogue of butadiyne. This species is characterized by a conjugated B≡N─N≡B moiety, a structural feature that enables the controlled release of N2 when it is exposed to organic nitriles. Furthermore, the N2 unit in 1 could be reduced to an ammonium salt via cleavage of the BN triple bond. Our work shows a rare example of an unsaturated BN system, serving as a platform for both the release and reduction of N2. This discovery opens new pathways and holds substantial influence on the future design of functional main group N2 species.
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Affiliation(s)
- Rui Guo
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China
| | - Chaopeng Hu
- Department of Chemistry and Research Center for Chemical Biology and Omics Analysis, College of Science, Southern University of Science and Technology, Shenzhen 518055, China
| | - Qianli Li
- School of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng 252059, China
| | - Liu Leo Liu
- Department of Chemistry and Research Center for Chemical Biology and Omics Analysis, College of Science, Southern University of Science and Technology, Shenzhen 518055, China
| | - Chen-Ho Tung
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China
| | - Lingbing Kong
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China
- State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin 300071, China
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5
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Bao M, Dai Y, Liu C, Su Y. Acid/Base-Free Acyclic Anionic Oxoborane and Iminoborane Bearing Diboryl Groups. Inorg Chem 2022; 61:11137-11142. [PMID: 35815522 DOI: 10.1021/acs.inorgchem.2c00966] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Anionic oxoboranes and neutral iminoboranes, which are isoelectronic to ketones and alkynes, respectively, have attracted much attention because of their unique structures and various reactivity. However, acid/base-free oxoboranes and iminoboranes are still limited, and readily accessible examples with diverse electronic and steric characteristics are highly desirable. Herein, we report the first syntheses of the acyclic anionic oxoborane 2 and iminoborane 4 bearing two boryl ligands, both of which are acid/base-free. Spectroscopic analysis, X-ray crystallography, and theoretical calculations reveal that 2 and 4 possess a polarized terminal B═O double bond and central B≡N triple bond, respectively.
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Affiliation(s)
- Manling Bao
- College of Chemistry, Chemical Engineering and Materials Science, School of Radiation Medicine and Protection, Soochow University, Suzhou 215123, P. R. China
| | - Yuyang Dai
- College of Chemistry, Chemical Engineering and Materials Science, School of Radiation Medicine and Protection, Soochow University, Suzhou 215123, P. R. China
| | - Chunmeng Liu
- College of Chemistry, Chemical Engineering and Materials Science, School of Radiation Medicine and Protection, Soochow University, Suzhou 215123, P. R. China
| | - Yuanting Su
- College of Chemistry, Chemical Engineering and Materials Science, School of Radiation Medicine and Protection, Soochow University, Suzhou 215123, P. R. China.,State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210023, P. R. China
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Abstract
Borenium ions are strong Lewis acids because of the positive charge on boron. While their high reactivity had long restricted their role in organic synthesis to stoichiometric reagents, in the past ten years the introduction of suitable supporting ligands, such as N-heterocyclic carbenes, has enabled them to function as competent catalysts for various organic transformations involving the activation of strong covalent bonds, such as H-H, Si-H, B-H, C-H and C-C bonds. This review provides an overview of the recent advances in borenium-catalysed reactions with emphasis on catalyst synthesis, methodology development and mechanistic insight.
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Affiliation(s)
- Xinyue Tan
- Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Department of Chemistry, Fudan University, Songhu Road 2005, Shanghai, 200438, P. R. China.
| | - Huadong Wang
- Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Department of Chemistry, Fudan University, Songhu Road 2005, Shanghai, 200438, P. R. China.
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7
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Guo R, Zhang X, Li T, Li Q, Ruiz DA, Liu LL, Tung CH, Kong L. Unraveling the reactivity of a cationic iminoborane: avenues to unusual boron cations. Chem Sci 2022; 13:2303-2309. [PMID: 35310477 PMCID: PMC8864711 DOI: 10.1039/d2sc00002d] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2022] [Accepted: 01/26/2022] [Indexed: 11/21/2022] Open
Abstract
A cationic terminal iminoborane [Mes*N
Created by potrace 1.16, written by Peter Selinger 2001-2019
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B ← IPr2Me2][AlBr4] (3+[AlBr4]−) (Mes* = 2,4,6-tri-tert-butylphenyl and IPr2Me2 = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) has been synthesized and characterized. The employment of an aryl group and N-heterocyclic carbene (NHC) ligand enables 3+[AlBr4]− to exhibit both B-centered Lewis acidity and BN multiple bond reactivities, thus allowing for the construction of tri-coordinate boron cations 5+–12+. More importantly, initial reactions involving coordination, addition, and [2 + 3] cycloadditions have been observed for the cationic iminoborane, demonstrating the potential to build numerous organoboron species via several synthetic routes. An NHC-stabilized aryliminoboryl cation exhibits both boron-centered Lewis acidity and multiple bond reactivity and could be utilized as an effective synthon for unusual cationic boron species.![]()
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Affiliation(s)
- Rui Guo
- School of Chemistry and Chemical Engineering, Shandong University Jinan 250100 P. R. China
| | - Xin Zhang
- Department of Chemistry and Shenzhen Grubbs Institute, Southern University of Science and Technology Shenzhen 518055 P. R. China
| | - Tong Li
- School of Chemistry and Chemical Engineering, Shandong University Jinan 250100 P. R. China
| | - Qianli Li
- School of Chemistry and Chemical Engineering, Liaocheng University Liaocheng 252059 P. R. China
| | - David A Ruiz
- Department of Chemistry and Shenzhen Grubbs Institute, Southern University of Science and Technology Shenzhen 518055 P. R. China
| | - Liu Leo Liu
- Department of Chemistry and Shenzhen Grubbs Institute, Southern University of Science and Technology Shenzhen 518055 P. R. China
| | - Chen-Ho Tung
- School of Chemistry and Chemical Engineering, Shandong University Jinan 250100 P. R. China
| | - Lingbing Kong
- School of Chemistry and Chemical Engineering, Shandong University Jinan 250100 P. R. China .,State Key Laboratory of Elemento-Organic Chemistry, Nankai University Tianjin 300071 P. R. China
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8
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Dubey G, Mahawar N, Singh T, Saha N, Sahoo SC, Bharatam PV. Thiazetidin-2-ylidenes as four membered N-heterocyclic carbenes: theoretical studies and the generation of complexes with N + center. Phys Chem Chem Phys 2022; 24:629-633. [PMID: 34933326 DOI: 10.1039/d1cp04732a] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Thiazetidin-2-ylidenes have been designed as four membered N-heterocyclic carbenes (NHCs) using quantum chemical studies. These species are smaller analogs of thiazol-2-ylidenes, possess high singlet stability (57 kcal mol-1) and large nucleophilicity (3.4 eV). The possible existence of these carbenes has been established by synthesizing and crystalizing compounds with NHC→N+←(thiazetidin-2-ylidene) coordination bonds.
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Affiliation(s)
- Gurudutt Dubey
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Sector 67, S.A.S. Nagar-160062, Punjab, India.
| | - Nutan Mahawar
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Sector 67, S.A.S. Nagar-160062, Punjab, India.
| | - Tejender Singh
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Sector 67, S.A.S. Nagar-160062, Punjab, India.
| | - Nirjhar Saha
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Sector 67, S.A.S. Nagar-160062, Punjab, India.
| | - Subash C Sahoo
- Department of Chemistry, Panjab University, Sector 14, Chandigarh, 160014, India
| | - Prasad V Bharatam
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Sector 67, S.A.S. Nagar-160062, Punjab, India.
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9
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Koner A, Sergeieva T, Morgenstern B, Andrada DM. A Cyclic Iminoborane-NHC Adduct: Synthesis, Reactivity, and Bonding Analysis. Inorg Chem 2021; 60:14202-14211. [PMID: 34374528 DOI: 10.1021/acs.inorgchem.1c01583] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Lewis-base coordinated iminoborane adducts, in contrast to their isoelectronic analogue imines, remain largely unexplored given the lack of efficient synthetic strategies for generating robust compounds. Herein, we report the preparation of a cyclic amino iminoborane carbene complex 2 obtained in quantitative yield by adding NHC to the 1,8-(trimethylsilyl)aminonaphthalene complex of boron 1 to induce the elimination of trimethylsilyl chloride (TMSCl). The iminoborane-NHC adduct 2 shows unprecedented thermal stability both in the solid and solution phases, due to the rigid, pre-established geometry of the 1,8-diaminonaphthalene scaffold. Theoretical calculations reveal an exceptionally strong iminoborane-NHC bond as a consequence of the enhanced boron-center acidity in combination with the lower steric and electronic shielding. We show that the chemical bond can be understood as donor-acceptor interaction, leading to a different kind of electronic situation of the B═N π-bond. The high conjugation between the pz-lone pair of the tricoordinated sp2 hybridized N atom and the B═N π-system results in a particularly long B═N double bond distance. Taking advantage of the pendant lone pair of the dicoordinated sp2 hybridized N atom, the iminoborane-NHC adduct gives access to NHC-stabilized borenium cation 3 through the reaction with trimethylsilyl triflate (Me3SiOTf) or to the gallium adduct 4 by reacting with GaCl3. Incorporating an iminoborane functional group into a π-conjugated system brings a new bonding situation for broadening the scope of BN-containing polyaromatic systems.
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Affiliation(s)
- Abhishek Koner
- Inorganic and Computational Chemistry Group, Universität des Saarlandes, Campus C4.1, D-66123 Saarbrücken, Germany
| | - Tetiana Sergeieva
- Inorganic and Computational Chemistry Group, Universität des Saarlandes, Campus C4.1, D-66123 Saarbrücken, Germany
| | - Bernd Morgenstern
- Inorganic and Computational Chemistry Group, Universität des Saarlandes, Campus C4.1, D-66123 Saarbrücken, Germany
| | - Diego M Andrada
- Inorganic and Computational Chemistry Group, Universität des Saarlandes, Campus C4.1, D-66123 Saarbrücken, Germany
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10
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Gao H, Li Q, Cui P, Tung CH, Kong L. Facile Access to Alkylideneborane and Diborabutadiene N-Heterocyclic Carbene Complexes. Inorg Chem 2021; 60:8432-8436. [PMID: 34043317 DOI: 10.1021/acs.inorgchem.1c00866] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
A facile route to synthesis of B═C double-bonded systems has been developed. Specifically, both dibromofluorenylborane (FluH-BBr2) and a 1,1-dibromo-2,2-difluorenyldiborane/dimethyl sulfide adduct [(FluH)2B-BBr2(SMe2)] could be smoothly dehydrobrominated and subsequently coordinated by N-heterocyclic carbenes (NHCs) with formation of the respective alkylideneborane 1 and diborabutadiene 3. The electronic structures of 1 and 3 are interrogated and compared with those of base-free counterparts through density functional theory calculations.
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Affiliation(s)
- Hao Gao
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, P. R. China
| | - Qianli Li
- School of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng 252059, P. R. China
| | - Ping Cui
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, P. R. China
| | - Chen-Ho Tung
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, P. R. China
| | - Lingbing Kong
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, P. R. China
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11
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Borthakur B, Ghosh B, Phukan AK. The flourishing chemistry of carbene stabilized compounds of group 13 and 14 elements. Polyhedron 2021. [DOI: 10.1016/j.poly.2021.115049] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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12
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Li B, Wölper C, Haberhauer G, Schulz S. Synthesis and Reactivity of Heteroleptic Ga-P-C Allyl Cation Analogues. Angew Chem Int Ed Engl 2021; 60:1986-1991. [PMID: 33034935 PMCID: PMC7894565 DOI: 10.1002/anie.202012595] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Indexed: 11/28/2022]
Abstract
Oxidative addition of cyclic alkyl(amino)carbene-coordinated phosphinidenes (Me cAAC)PX to LGa affords gallium-coordinated phosphinidenes LGa(X)-P(Me cAAC) (L=HC[C(Me)N(2,6-i-Pr2 C6 H3 )]2 ; X=Cl 1, Br 2), which react with NaBArF 4 and LiAl(ORF )4 to [LGaP(Me cAAC)][An] (An=B(C6 H3 (CF3 )2 )4 3, B(C6 F5 )4 4, Al(OC(CF3 )3 )4 5). The cations in 3-5 show substantial Ga-P double bond character and represent heteronuclear analogues of allyl cations according to quantum chemical calculations. The reaction of 4 with 4-dimethylaminopyridine (dmap) to adduct 6 confirms the strong electrophilic nature of the gallium center, whereas 5 reacts with ethyl isocyanate with C-C bond formation to the γ-C atom of the β-diketiminate ligand and formation of compound 7.
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Affiliation(s)
- Bin Li
- Institute of Inorganic Chemistry and Center for Nanointegration Duisburg-Essen (CENIDE)University of Duisburg-EssenUniversitätsstrasse 5–745141EssenGermany
| | - Christoph Wölper
- Institute of Inorganic Chemistry and Center for Nanointegration Duisburg-Essen (CENIDE)University of Duisburg-EssenUniversitätsstrasse 5–745141EssenGermany
| | - Gebhard Haberhauer
- Institute of Organic Chemistry, University of Duisburg-EssenUniversitätsstrasse 5–745141EssenGermany
| | - Stephan Schulz
- Institute of Inorganic Chemistry and Center for Nanointegration Duisburg-Essen (CENIDE)University of Duisburg-EssenUniversitätsstrasse 5–745141EssenGermany
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13
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Li B, Wölper C, Haberhauer G, Schulz S. Synthesis and Reactivity of Heteroleptic Ga‐P‐C Allyl Cation Analogues. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202012595] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Bin Li
- Institute of Inorganic Chemistry and Center for Nanointegration Duisburg-Essen (CENIDE) University of Duisburg-Essen Universitätsstrasse 5–7 45141 Essen Germany
| | - Christoph Wölper
- Institute of Inorganic Chemistry and Center for Nanointegration Duisburg-Essen (CENIDE) University of Duisburg-Essen Universitätsstrasse 5–7 45141 Essen Germany
| | - Gebhard Haberhauer
- Institute of Organic Chemistry, University of Duisburg-Essen Universitätsstrasse 5–7 45141 Essen Germany
| | - Stephan Schulz
- Institute of Inorganic Chemistry and Center for Nanointegration Duisburg-Essen (CENIDE) University of Duisburg-Essen Universitätsstrasse 5–7 45141 Essen Germany
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14
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Guo R, Jiang J, Hu C, Liu LL, Cui P, Zhao M, Ke Z, Tung CH, Kong L. BNN-1,3-dipoles: isolation and intramolecular cycloaddition with unactivated arenes. Chem Sci 2020; 11:7053-7059. [PMID: 34122998 PMCID: PMC8159347 DOI: 10.1039/d0sc02162h] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The mono-base-stabilized 1,2-diboranylidenehydrazine derivatives featuring a 1,3-dipolar BNN skeleton are obtained by dehydrobromination of [ArB(Br)NH]2 (Ar = 2,6-diphenylphenyl (Dpp), Ar = 2,6-bis(2,4,6-trimethylphenyl)phenyl (Dmp) or Ar = 2,4,6-tri-tert-butylphenyl (Mes*)) with N-heterocyclic carbenes (NHCs). Depending on the Ar substituents, such species can be isolated as a crystalline solid (Ar = Mes*) or generated as reactive intermediates undergoing spontaneous intramolecular aminoboration of the proximal arene rings via [3 + 2] cycloaddition (Ar = Dpp or Dmp). The latter reactions showcase the 1,3-dipolar reactivity toward unactivated arenes at ambient temperature. In addition, double cycloaddition of the isolable BNN species with two CO2 molecules affords a bicyclic species consisting of two fused five-membered BN2CO rings. The electronic structures of these BNN species and the mechanisms of these cascade reactions are interrogated through density functional theory (DFT) calculations.
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Affiliation(s)
- Rui Guo
- School of Chemistry and Chemical Engineering, Key Laboratory of Colloid and Interface Chemistry of Ministry of Education, Shandong University Jinan 250100 P. R. China
| | - Jingxing Jiang
- School of Materials Science & Engineering, PCFM Lab, Sun Yat-sen University Guangzhou 510275 P. R. China
| | - Chenyang Hu
- Shenzhen Grubbs Institute and Department of Chemistry, Southern University of Science and Technology Shenzhen 518055 P. R. China
| | - Liu Leo Liu
- Shenzhen Grubbs Institute and Department of Chemistry, Southern University of Science and Technology Shenzhen 518055 P. R. China
| | - Ping Cui
- School of Chemistry and Chemical Engineering, Key Laboratory of Colloid and Interface Chemistry of Ministry of Education, Shandong University Jinan 250100 P. R. China
| | - Meihua Zhao
- School of Chemistry and Chemical Engineering, Key Laboratory of Colloid and Interface Chemistry of Ministry of Education, Shandong University Jinan 250100 P. R. China
| | - Zhuofeng Ke
- School of Materials Science & Engineering, PCFM Lab, Sun Yat-sen University Guangzhou 510275 P. R. China
| | - Chen-Ho Tung
- School of Chemistry and Chemical Engineering, Key Laboratory of Colloid and Interface Chemistry of Ministry of Education, Shandong University Jinan 250100 P. R. China
| | - Lingbing Kong
- School of Chemistry and Chemical Engineering, Key Laboratory of Colloid and Interface Chemistry of Ministry of Education, Shandong University Jinan 250100 P. R. China .,State Key Laboratory of Elemento-Organic Chemistry, Nankai University Tianjin 300071 P. R. China
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